1. Field of the Invention
The present invention relates to a laser light source, a laser oscillation method and a laser processing method suitable for processing use (processing, reformation, cleaning, and the like). Also, the present invention is effective for measurement of a long distance and destruction of an object to be measured which require a high output light source.
2. Related Background of the Invention
The laser light source is used not only for communication but also for processing. The laser light source for processing use (in particular, microfabrication) requires large mean power of the output laser light, excellent quality M2 of the output laser light, large peak power of the output laser light, and large pulse energy of the output laser light.
For example, a laser light source having been disclosed in “27-mJ nanosecond pulses in M2=6.5 beam from a coiled highly multimode Yb-doped fiber amplifier”, M.-Y Chen, et al., CLEO'2004 Technical Digest, CTuS4, or “Extended large-mode-areasingle-mode microstructured fiber laser”, Limpert, et al., CLEO'2004 Technical Digest, CMS6, is configured of a MOPA (Master Oscillator Power Amplifier) structure, which includes a light source section for outputting pulse laser light and an optical amplification section for amplifying and outputting pulse laser light output from the above light source section by means of an optical amplification medium, and can be employed for processing use.
Now, to perform laser processing on a processing object with precision, a pulse shape of the pulse laser light output from the laser light source is also important. For example, when performing laser processing of metal, it may be considered that, at an early stage, the metal is melted with peak power of a considerably low level in each pulse of pulse laser light, and thereafter, at a later stage, pulse energy is set high, so as to eliminate the melted metal by vaporization at a stroke. Also, it may be considered that two pulses of light, for example, are used as one set, and in each set, after processing by use of the pulse light in the first stage, reattachment of eliminated scrap is avoided by irradiating with the pulse light of low energy in the second stage. As such, it is preferable for processing use that the pulse laser light output from a laser light source can be set to a more suitable pulse shape, pulse intervals or pulse energy.
However, in the conventional laser light sources including the ones described in the above two papers, there has been no degree of freedom in regard to the above point. Owing to this, in laser processing using the conventional laser light sources, there may be the case that processing a processing object with precision cannot be performed.